1. Field of the Invention
The present invention relates to an exposure method of exposing a pattern which is shaped on a photomask or reticle (referred to as xe2x80x9cmaskxe2x80x9d hereinafter) to the light, thereby imaging the mask pattern on a photosensitive material, and also relates to an exposure apparatus (referred to as xe2x80x9calignerxe2x80x9d hereinafter) for executing the method. Especially, the invention relates to a preferable exposure method and aligner as an exposure technique applicable, for example, to the photolithographic process in the manufacture of a semiconductor integrated circuit (SIC), a liquid crystal display (LCD), a flexible printed circuit board, and so forth; and also used as a preferable exposure technique applicable, for example, to a scanner for use in a printing plate maker, an electronic copy machine, and so forth.
2. Prior Art
Among various kinds of aligners as used in the photolithographic process, one of the processes of manufacturing a semiconductor integrated circuit, a liquid crystal display, and so forth, there is an aligner called a projection aligner which exposes the exposure mask pattern on the photosensitive material with the help of an imaging optical system.
As one of aligners like the above, there is disclosed a projection aligner of the type wherein, for example, a mask and an object to be exposed (referred to as xe2x80x9cexposure objectxe2x80x9d hereinafter) which has a photosensitive material are supported by an identical stage such that their respective surfaces on which light is incident are approximately in an identical plane, and the light from a light source is first incident on the mask, and then, the light passing through the mask forms an image on the photosensitive material by using the imaging optical system (refer to the specification of U.S. Pat. No. 5,652,645).
This projection aligner carries out the so-called scan-exposure in which the optical system and the supporting device for supporting the mask and the exposure object are relatively and two-dimensionally moved. To put it more concretely, in this aligner, the supporting device is moved in an X-Y plane by means of an X-Y driving device, and in the exposure process, the supporting device is moved back and forth repeating the go-and-stop motion with a lateral movement therebetween by a scanning pitch (distance).
In this projection aligner, however, the X-Y driving device has to be constituted to control each of such movements of the supporting device as described above, for example, to control the movement each time or every time the supporting device starts the above movement and/or stops the above movement. Especially, in order to move the supporting device at a high speed by the X-Y driving device, it would be required to additionally prepare another device for eliminating or reducing the physical load put on the X-Y driving device due to the weight and inertia of the supporting device, which disadvantageously causes the entire scale of the aligner to be large.
Furthermore, if the supporting device capable of supporting the large size mask and exposure object is used, the weight of the supporting device increases, according to which the inertia thereof becomes larger. Consequently, the physical load acting on the X-Y driving device comes to further increase. If the physical load becomes large, there come out such problems that it becomes impossible to ignore the influence of the backlash or the like on the movement accuracy of the supporting device, that the durability of the X-Y driving device is degraded , and so forth.
On one hand, there is disclosed an aligner of the type wherein no X-Y driving device is used but the mask and the exposure object are continuously rotated to carry out the scan-exposure (refer to, for example, the specification of JP Patent Public Disclosure No. 6-74945). In this aligner, however, as the mask and the exposure object are arranged so as to be located on two different planes, respectively, at least a part of the projection optical system being located between the mask and the exposure object and are respectively rotated by different driving devices, there come out such problems as precise positioning between the mask and the exposure object becomes difficult, two driving devices have to be in synchronization with each other with high precision, eccentricity in rotation of the mask and the expose object has to completely removed, and so forth. Therefore, in order to obviate these problems, the driving mechanism can not help being complicated and expensive.
Accordingly, it is an object of the invention to reduce a physical load put on a driving mechanism for moving a supporting device for supporting a mask and an exposure object having a photosensitive material, and also to simplify the structure of the driving mechanism.
According to the invention, there is provided an exposure method of exposing an exposure mask pattern of a mask for exposure on a photosensitive material, which comprises: an incidence step of letting at least a part of light from a light source for exposure be incident on the mask supported by a supporting device; an imaging step of letting transmission light from the mask be incident on the photosensitive material supported by the supporting device from a direction which is different from a direction of light incident on the mask, thereby causing the transmission light to form an image on the photosensitive material; a rotation step of rotating the supporting device such that a position of irradiation to the mask caused by light from the light source changes along a circumferential direction of the supporting device; and an irradiation position changing step of changing the irradiation of light to the mask as well as a position of irradiation of light to the photosensitive material along a direction which is different from the ciucumferential direction of the supporting device in a rotating plane of the supporting device while the supporting device is being rotated.
According to the invention, there is further provided an aligner for exposing an exposure pattern of a mask on a photosensitive material, comprising: a supporting device having a first supporting portion supporting the mask such that the mask receives at least a part of light from a light source for exposure and a second supporting portion supporting the photosensitive material such that the photosensitive material receives transmission light from the mask from a direction which is different from a direction of light incident on the mask; an imaging optical system which guides the transmission light from the mask, to the photosensitive material so as to form an image on the photosensitive material; a rotation unit for rotating the supporting device such that a position of irradiation to said mask caused by light from the light source changes along a circumferential direction of the supporting device; and an irradiation position changing device which changes the position of irradiation of light to the mask as well as a position of irradiation of light to the photosensitive material along a direction which is different from the circumferential direction of the supporting device in a rotating plane of the supporting device while the supporting device is being rotated.
The supporting device supporting the mask and the photosensitive material is rotated by the rotating device such that the position of irradiation to the mask caused by the light from the light source as well as the position of irradiation to the photosensitive material caused by the transmission light from the mask change along the circumferential direction of the supporting device. Furthermore, the irradiation position changing device changes the position of irradiation to the mask caused by the light from the light source and the position of irradiation to the photosensitive material by the transmission light from the mask change, in the rotating plane of the supporting device, along a direction which is different from the circumferential direction of the supporting device.
According to the invention, it is good enough for the supporting device to be continuously rotated by the rotating device, for example, always only in one direction. Therefore, a physical load as put on a driving device for moving the supporting device is reduced, which enables high speed scan-exposure comparing to the prior art scan-exposure making use of the X-Y driving device, thereby the throughput is improved.
It is possible to pass the transmission light from the mask via a plurality of reflecting mirrors and through at least one imaging lens, thereby changing an advancing direction of the transmission light and forming an image on the photosensitive material, and moving at least one of the plural reflecting mirrors.
It is possible to move the reflecting mirror toward the axis of rotation of the supporting device. It is also possible to move the imaging lens together with the reflecting mirror.
It is possible to pass the transmission light from the mask via a plurality of reflecting mirrors and through at least one concave mirror, thereby changing an advancing direction of the transmission light from the mask and forming an image on the photosensitive material, and moving the concave mirror. In this case, it is possible to move the concave mirror toward the axis of rotation of the supporting device.
The mask and the photosensitive material may be arranged on the supporting device such that they are rotationally symmetric with regard to the axis of rotation of the supporting device.
The irradiation position may be changed, while an optical path between the mask and the photosensitive material is kept constant.